U.S. patent number 4,836,305 [Application Number 07/079,461] was granted by the patent office on 1989-06-06 for drill pipes and casings utilizing multi-conduit tubulars.
This patent grant is currently assigned to Pangaea Enterprises, Inc.. Invention is credited to Harry B. Curlett.
United States Patent |
4,836,305 |
Curlett |
June 6, 1989 |
Drill pipes and casings utilizing multi-conduit tubulars
Abstract
An improved drill pipe utilizing multi-conduit tubulars is
provided. A seal subassembly (644) is constructed and arranged so
as to receive a plurality of similar tubular conduits (626, 630).
The similar tubular conduits (626, 630) are inserted into both ends
of the seal subassembly (644). At one end, the tubular conduits
(630) are threadably attached to the seal subassembly (644), while
at the opposite end, the tubular conduits (626) are slidably
attached to the seal subassembly (644). T-rings seals (674) are
provided to insure sealing engagement of the tubular conduits to
the seal subassembly (644). A collar (638) is provided to join a
drill pipe (596) to one end of the seal subassembly (644). A lift
subassembly (682) is provided to attach the other end of the seal
subassembly (644) to another drill pipe (598). The seal subassembly
(644) is constructed so as to allow the tubular conduits to be of
strength sufficient to withstand pressure and compression forces
only. Tension and torsional forces are handled entirely by the
drill pipe outer casings (614, 616), the collar (638), the seal
subassembly (644), and the lift subassembly (682).
Inventors: |
Curlett; Harry B. (Dallas,
TX) |
Assignee: |
Pangaea Enterprises, Inc.
(Dallas, TX)
|
Family
ID: |
22150708 |
Appl.
No.: |
07/079,461 |
Filed: |
July 30, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
730831 |
May 6, 1985 |
4683944 |
Aug 4, 1987 |
|
|
Current U.S.
Class: |
175/215;
175/320 |
Current CPC
Class: |
E21B
17/18 (20130101); E21B 21/08 (20130101); E21B
21/12 (20130101); F16L 39/06 (20130101); E21B
21/02 (20130101); E21B 17/003 (20130101); F16L
39/04 (20130101) |
Current International
Class: |
F16L
39/06 (20060101); E21B 17/00 (20060101); E21B
21/02 (20060101); E21B 21/08 (20060101); E21B
21/00 (20060101); E21B 17/18 (20060101); E21B
21/12 (20060101); F16L 39/00 (20060101); F16L
39/04 (20060101); E21B 017/02 (); E21B
017/18 () |
Field of
Search: |
;175/215,320,324
;166/242 ;174/47 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Neuder; William P.
Attorney, Agent or Firm: Baker, Mills & Glast
Parent Case Text
RELATED APPLICATIONS
This Application is a continuation-in-part of application Ser. No.
730,831, filed May 6, 1985, due to become U.S. Pat. No. 4,683,944
issuing Aug. 4, l987 and entitled "Drill Pipes and Casings
Utilizing Multi-Conduit Tubulars."
Claims
What is claimed is:
1. A drill pipe for use in drilling subterranean formations,
comprising:
an outer casing threadable at both ends thereof for connection to
other similar casings, said outer casing being adapted to withstand
torque and tensile loads of other pipes connected thereto;
at least one tubular conduit floating within said outer casing so
as to be substantially relieved of tensile loads carried by said
outer casing, said conduit adapted for carrying pressurized fluids
therethrough;
a coupler for coupling said outer casing to the other similar outer
casing of other drill pipes, said coupling having means for
transferring torque and tensile loads from one said outer casing to
another, and means for supporting the end of said conduit within
said outer casing so as to prevent transfer of tensile loads
through said conduit; and
means for sealing said conduit to other similar conduits in said
other similar outer casing for providing a continuous sealed
conduit for carrying pressurized fluids.
2. The drill pipe of claim 1, wherein said outer casing is pierced
so as to equalize internal and external pressures.
3. The drill pipe of claim 1, wherein said means for transferring
loads between said outer casings comprises:
a collar having a first and second threaded end, one said end being
threadably secured to said outer casing;
a seal subassembly having a first and second threaded end, one said
end being threadably secured to said collar; and
a lift subassembly having a first and second threaded end
threadably secured to said seal subassembly and threadably secured
to said other similar outer casing.
4. The drill pipe of claim 1, wherein said means for sealing said
conduit to a similar conduit in another outer casing comprises:
a seal subassembly having at least one bore for sealing one end of
said conduit, and for sealing another end of said similar conduit;
and
said bore has annular grooves, each for receiving an elastomeric
seal.
5. The drill pipe of claim 4, wherein said elastomeric seal is a
T-ring type seal.
6. The drill pipe of claim 5, wherein said T-ring seal includes
anti-extrusion rings.
7. The drill pipe of claim 3, wherein said lift subassembly further
includes an external annular recess for facilitating drill pipe
handling, and an end edge for positioning said drill pipe.
8. An improved drill pipe utilizing multi-conduit tubulars,
comprising:
an outer casing having first and second ends;
a central conduit housed within said outer casing and having a
length somewhat longer than said outer casing so as to protrude
from said first and second ends of said outer casing;
a plurality of radially arranged radial tubes disposed within said
outer casing and having a length somewhat longer than said outer
casing but shorter than said central conduit, and disposed between
said outer casing and said central conduit;
a seal subassembly having first and second ends constructed and
arranged so as to sealingly receive and support said central
conduit and said radial tubes;
a collar for connecting said outer casing to said seal subassembly;
and
a lift subassembly for connecting said seal subassembly to another
similar outer casing, whereby said radial tubes and said conduits
are sealed by said seal subassembly which is in turn connected to
said outer casings by said collar on one end thereof and to said
lift subassembly on the other end thereof.
9. The improved drill pipe of claim 8, wherein said outer casing is
pierced therethrough so as to equalize internal and external fluid
pressures.
10. The improved drill pipe of claim 8, wherein said seal
subassembly further comprises:
a cylinder having an external diameter and an internal diameter
defining a thick sidewall;
an axial central bore formed by said internal diameter for
receiving said central conduit; and
a plurality of radial channels formed in said thick sidewall for
receiving said radially arranged radial tubes.
11. The improved drill pipe of claim 10, wherein said central bore
and said radial channels have sealing means for interconnecting one
end of said central conduit and of said radial tubes to another end
of another central conduit and other radial tubes.
12. The improved drill pipe of claim 11, wherein said sealing means
comprises elastomeric seals inserted in annular grooves formed in
said seal subassembly.
13. The improved drill pipe of claim 12, wherein said central bore
further includes a reduced diameter section in which one said
annular groove is formed, said reduced diameter section being
effective to prevent flowing of said elastomeric seal.
14. The improved drill pipe of claim 13, wherein said reduced
diameter section has a polished surface for engagement with said
central conduit.
15. The improved drill pipe of claim 12, wherein each said radial
channel includes a reduced diameter section in which an annular
groove is formed, said reduced diameter section being effective to
prevent said elastomeric seals from flowing.
16. The improved drill pipe of claim 15, wherein each said reduced
diameter section, has a polished surface engageable with a
respective one of said radial tubes.
17. The improved drill pipe of claim 12, wherein said elastomeric
seals comprise T-ring seals.
18. The improved drill pipe of claim 17, wherein said T-ring seals
include anti-extrusion rings.
19. The improved drill pipe of claim 8, wherein said lift
subassembly further includes an outer annular recess for
facilitating drill pipe handling, and an end edge for positioning
said drill pipe.
20. An improved apparatus for coupling drill pipes utilizing
independent tubular conduits, comprising:
a seal subassembly for sealingly receiving and supporting one set
of independent tubular conduits in a floating manner in one end of
said seal subassembly, and for sealingly receiving and supporting a
second set of independent tubular conduits in a fixed manner in
another end thereof;
a collar for connecting the one end of said seal subassembly to a
first drill pipe; and
a lift subassembly for connecting to another end of said seal
subassembly and to a second drill pipe.
21. A method for coupling drill pipes utilizing independent tubular
conduits, comprising the steps of:
inserting an end of a first said tubular conduit into a seal
subassembly so as to sealingly support said conduit;
connecting a lift subassembly to said seal subassembly;
connecting a first drill pipe to said lift subassembly;
inserting an end of a second tubular conduit into said seal
subassembly so as to slideably and sealingly engage said second
tubular conduit to said seal subassembly and to connect said first
tubular conduit to said second tubular conduit;
connecting a collar to a second said drill pipe; and
connecting said collar to said seal subassembly.
22. An improved drill pipe string utilizing multi-conduit tubulars,
comprising:
a pair of tubular outer casings each having first and second
ends;
a tubular central conduit protruding from said first and said
second ends of each of said outer casings;
each of said tubular central conduits having first and second
threaded ends;
a plurality of radial tubes each having a first end and a second
threaded end extending from said first and second end of each of
said outer casing;
said plurality of radial tubes being disposed respectively between
each of said outer casings and each of said central conduits;
said radial tubes having a length somewhat longer than each of said
respective outer casing but shorter than each of said respective
central conduits;
a seal subassembly having first and second ends being disposed
between said first and second end of said outer casing;
said seal subassembly having a central bore for receiving said
central conduits;
said seal subassembly having a plurality of hollow tubular channels
between said central bore and an external surface of said seal
subassembly;
said seal subassembly having means for receiving said central
conduits and said plurality of radial tubes;
said means for receiving said central conduits and said plurality
of radial tubes comprising:
said first end of said seal subassembly having slideable means for
receiving said first ends of said central conduits and said first
ends of said plurality of radial tubes; and
said second end of said seal subassembly having thread means for
receiving said second threaded ends of said central conduits and
said second threaded ends of said plurality of radial tubes;
a collar for connecting said first end of said outer casing to said
first end of said seal subassembly;
a lift subassembly for attaching said second end of said seal
subassembly to said second end of said outer casing;
said lift subassembly having an external annular recess;
each of said outer casings being pierced to equalize the pressure
internal and external to said casings;
said plurality of tubular channels and said tubular central bore of
said seal subassembly having annular grooves in said first and
second ends for receiving a T-ring seal;
said T-ring seal being secured by anti-extrusion rings; and
said plurality of tubular channels and said central tubular bore of
said seal subassembly having annular ridges located between said
annular grooves and said second end adjacent to said annular
grooves, whereby the second end of the central conduit is
threadably attached to the second end of the seal subassembly, the
second end of the plurality of radial tubes is threadably attached
to the second end of the seal subassembly, the first end of the
lift subassembly is attached to the second end of the seal
subassembly, a first outer casing is slipped over the central
conduit and the radial tubes so that the second end of the casing
is attached to the second end of the lift subassembly, the first
end of the collar is attached to the first end of a second outer
casing so that the first end of the radial tubes and the first end
of the central conduit protrude beyond the second end of the
collar, the first end of the central conduit is then inserted into
the first end of the seal subassembly, the first end of the second
outer casing is rotated so that the first end of the radial tubes
is properly aligned with the first end of the seal subassembly and
the collar is then turned so as to force the first end of the
second outer casing toward the first end of the seal subassembly,
thus inserting the first end of the radial tubes and the central
conduit into their respective channels and bores in the seal
subassembly.
23. The drill pipe of claim 1, further including a plurality of
said tubular conduits radially arranged within said outer casing.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates in general to well drilling
operations, and more particularly, relates to methods and apparatus
for boring subterranean holes, injecting high pressure and low
pressure fluids into multi-conduit tubulars and monitoring downhole
parameters to control drilling or production operations and thereby
optimize efficiency.
BACKGROUND OF THE INVENTION
Basic well drilling operations have remained unchanged over the
years insofar that a number of connected drill pipes, forming a
drill string, are rotated to turn a drill bit and abrade the earth
formation. During drilling, it is necessary to measure various
drilling parameters such as drilling formation, inclination,
temperature, PH and the like. Because the drill string rotates, and
in many cases thousands of feet below the earth's surface, gaining
instantaneous downhole information has been a constant problem.
For example, the most efficient drilling operation occurs when the
characteristics of the formation are known to the drilling operator
For different types of formations, such as rocks, soil or fluids
and gases, it may be desirable to alter the surface operations to
effectively deal with the type of formation in which the drill bit
is presently encountering. Traditionally, the formation chips
eroded by the drill bit are carried uphole in the annulus around
the drill string by fluids pumped downwardly through drill pipe.
The inspection of these chips, however, provides unreliable
information of formation presently being drilled, as it may take a
substantial period of time for the chips to ascend to the
surface.
It is known in the art, i.e., U.S. Pat. No. 3,419,092, by Elenburg,
that a dual passage drill pipe, in the nature of inner and outer
concentric pipes, can be employed to pump aerated drilling fluid
down one conduit to decrease the hydrostatic head at the drill bit
and thereby accelerate the velocity by which the cuttings are moved
upwardly to the surface in the other pipe conduit. In this manner,
the cutting chips which represent the type of formation being
drilled arrive at the surface more quickly, in which event the
drilling operations can be modified accordingly. While fluid
commutation to the various concentric conduits of the Elenburg-type
drill pipe is relatively uncomplicated, the number of such conduits
which can be employed is limited by practical considerations of the
drill pipe construction.
In U.S. Pat. No. 2,951,680 by Camp et al., it is recognized that a
non-concentric multi-conduit drill pipe may be employed to increase
the number of conduits. However, to accommodate fluid commutation,
the fluid passage transition from the conduits to the drill pipe
end is convoluted into conventional concentric circular passages.
As a result, commutation of different fluids into the respective
conduits of the Camp et al. drill pipe was provided at the expense
of complicating the manufacturability of the pipe, and thus making
it costly.
Those skilled in the art have thus recognized the advantage of
using multi-conduit drill pipes, but such pipes have not met with
widespread success for a number of reasons. One drawback
encountered in connecting such pipes together is the manner in
which the conduits of one pipe are sealed to the conduits of
another pipe. Conventional sealing arrangements include "O" rings
or chevron seal rings (U.S. Pat. No. 2,951,680) or traditional
packing (U.S. Pat. No. 3,077,358). Because of the type of seal used
and the manner in which such seals have been used, the fluid
pressure which the seals can withstand is generally under 7,500
p.s.i. differential.
It is apparent, therefore, that there is a need for a high-pressure
multi-conduit drill pipe in which the number of conduits is not
limited, nor is the structure or fabrication of the pipe unduly
complicated or costly.
Moreover, there is an urgent need to monitor downhole drilling
operations, instanteously transmit the results thereof uphole, and
combine the transmission medium with the drill pipe in such a
manner that the drill pipe fluid carrying capability is not
severely compromised.
It has been heretofore proposed to employ the central bore of the
drill pipe as a chamber in which an electrical conductor is
situated Exemplary of such practice is that disclosed in U.S. Pat.
Nos. 2,795,397 and 3,904,840. According to this practice, however,
the conductor insulation is subjected to the drill fluid, or
expensive shielding must be used.
An attendant problem with the use of electrical conductors in the
fluid-carrying bore is the isolation from the fluids of the
electrical connections which connect lengths of conductors
together. Elaborate and unusual techniques have been resorted to in
order to circumvent this problem. To further compound the problem,
the connection of conductors from one drill pipe to another is
exacerbated in those types of pipes which require one section to be
rotatably screwed into the other. In U.S. Pat. No. 2,748,358, this
concern is dealt with by leaving ample cable length so that it may
be twisted along with the pipe. In other instances, i.e., U.S. Pat.
No. 3,879,097, the electrical cable is carried within the central
bore along a majority of its length, except at the ends thereof
where the cable is routed through the pipe sidewall to ring shaped
contacts on the pipe ends. The number of conductors is obviously
limited when resort is had to this technique.
Exemplary of prior provisions for connecting together a plurality
of conductors at the pipe ends is that disclosed in U.S. Pat. No.
2,750,569. In the noted patent, the electrical cable is routed
through the fluid carrying bore. This leaves the cable, as well as
the connector, susceptible to the corrosive or erosive effects of
the drill fluid.
Further concerns in the well drilling art which contribute to the
overall expense incurred relate to the composition of the drilling
"mud". The mud must be periodically adjusted with different
materials and chemicals to effectively change its density,
viscosity or other properties. This change can only be accomplished
gradually as the mud circulates from the bit area upwardly through
surface equipment. In some cases, such as an imminent well blow
out, the density of the mud must be altered very quickly to prevent
such an occurrence. As a consequence, many blow outs cannot be
averted with known techniques. A need has thus arisen for a drill
string construction which allows the prompt altering of drill mud
pressure to control blow outs and to otherwise enhance
drilling.
Even after the drilling operation has been completed there is a
need to monitor downhole parameters during the production phase for
Well management purposes. Conventional well casings have heretofore
afforded a high degree of integrity to the well bore, but, are
ill-equipped to provide passageways for wires, gases or liquids
other than the fluid pumped upwards. As a stopgap measure,
telemetry wires have been secured to the outer periphery of the
casing by metal or plastic bands and extended downhole to telemetry
equipment. It is also well known to provide parasitic pipes
external to the casing for carrying air pressure to create
artificial lift downhole.
As a result, there is a need for a multi-conduit well casing
through which the production fluid can be pumped, as well as a
plurality of additional conduits for housing telemetry wires and
carrying solvents, antifreeze solutions and a host of other
fluids.
SUMMARY OF THE INVENTION
In accordance with the present invention, methods and apparatus are
provided for commutating a number of high and low pressure fluids
through unique drill pipes having uniform conduits therethrough,
and for transmitting electrical signals or power downhole to
sensors to gather information relating to the subterranean
formation.
In accordance with the invention, a multi-conduit drill pipe is
provided with a uniform cross-sectional configuration throughout
the pipe, thereby lending the construction thereof to extrusion
methods. Cross-sectionally, the drill pipe includes an outer
cylindrical wall, an inner cylindrical wall defining a central
bore, and a plurality of other conduits between the inner and outer
walls. In the preferred form of the invention, the drill pipe has
an outer casing connected by coupler means to other similar outer
casings of the drill string to transmit torque and to provide the
tensile strength for suspending a drill string many feet into the
earth. Supported within the outer casing is a cluster of inner
tubulars, including plural radial tubulars disposed around a larger
central tubular. The inner tubulars do not carry tension or
torsional loads, but rather sustain the compression or burst
pressures of fluids carried within the tubulars. Each inner tubular
is supported at its ends by a seal subassembly which is fixed to
the outer casing. A telescopic sealing arrangement is provided
between one end of each inner tubular and the coupler to allow the
outer casings to extend somewhat under tension loads, without also
causing extension of the inner tubulars. The other end of the inner
tubulars are threaded into a coupler secured to the other end of
the outer casing.
One conduit includes electrical wires therein and a connector fixed
in the conduit at each pipe end. Because it may be desirable to
utilize various conduits for different fluids, or electrical
circuits, the pipes each include on opposite ends an index lug and
an index recess so that the particular conduits of each pipe, when
joined, are maintained aligned. In addition to the index lugs and
recesses, the pipe ends also include different lugs and recesses
for driving one pipe with the other.
According to the invention, a seal with passages is provided, which
seal has a cross-sectional shape similar to that of the drill pipe,
and wherein one such passage includes an intermediate electrical
connector for joining the circuits of each pipe together An
elastomer on each side of the seal assures a high pressure
integrity between each conduit when the pipes are joined.
In accordance with a further aspect of the invention, the drill
pipes are joined together with the seal therebetween by a threaded
coupling collar with uniform diameter internal threads at one end
thereof and uniform diameter internal threads at the other end
thereof but each such coupling collar end having a different
diameter and thread pitch. Each end of a drill pipe section
includes threads with diameters and pitches corresponding to that
of the coupling collar. This aspect enables the drill pipes to be
coupled together by a differential thread action which
compressively squeezes the seal in sealing engagement between the
adjacent pipes.
In accordance with a further feature of the invention, a plurality
of fluids from respective sources are commutated to various drill
pipe conduits by a fluid commutator having a shaft rotating in a
manifold to which the different fluid sources are connected. The
cylindrical shaft has internal passages which individually
correspond to the respective drill pipe conduits. Each commutator
shaft passage also opens into an inlet port on the cylindrical side
of the shaft. In fluid communication around the various inlet
ports, which are axially spaced along the commutator shaft, are
corresponding annular grooves in the manifold. Each commutator
shaft passage is thus connected through its manifold groove to a
fluid source. With this arrangement, various drill pipe conduits
are in continuous communication with a selected fluid source.
With regard to a related feature of the invention, the fluid
commutator shaft is coupled to the drill pipe string through an
adaptor which connects each commutator shaft passage, and thus a
fluid source, to selected ones of the drill pipe conduits. Thus, a
number of adaptors may be kept on hand and interchanged with others
to connect the various fluid sources through the commutator shaft
to desired ones of conduits in the drill pipe string.
With regard to a still further, aspect of the invention, a quill
section of the gooseneck swivel includes a quill shaft which
further includes an electrical connector terminating the drill pipe
electrical wires. A number of slip rings corresponding to the
number of wires carried in the drill pipe are placed around the
quill shaft, each such slip ring being connected to one of the
wires in the drill pipe. Stationary brush means contact the slip
rings and communicate the downhole electrical responses to surface
monitor equipment.
From the foregoing, an improved method of drilling is made
possible, in which high pressure fluids can be independently
injected into one or more drill pipe conduits to, for example,
simultaneously erode the formation, clean and cool the drill bit or
the drill bit path, while other lower pressure fluids in other
conduits are combined downhole with gases in yet other conduits to
decrease the downhole hydrostatic pressure. Simultaneously, drill
bit or pipe sensors may communicate to surface monitor equipment
information regarding temperature, pressure, inclination, etc which
information may be immediately used to alter the drilling
operation.
Such information may further be used, for example, to control the
application of annulus pressure to liquid or mud and avert a well
blow out. In addition, and according to the invention, should a
potential well blow out be detected, a pump may be activated to
apply pressure to counteract the excessive upward flow in the
central passage of the drill pipe. Moreover, a feature of the
invention includes an annular accumulator which can adjust the
pressure exerted on the liquid in the wellbore annulus, and thereby
maintain a given pressure on the annulus liquid. The ability to
apply pressure to the liquid in the annulus of the well has the
effect of increasing the density of the mud at the bottom of the
well without having to recirculate the mud and add materials to
weight it up.
A parallel feature of the invention which is of paramount
importance is the provision of a multi-conduit well casing having
many attributes of the drill pipe, including a generally larger
central bore to accommodate a large volume of production fluid.
Well production management is enhanced by the ability to monitor
many downhole parameters and simultaneously inject fluids and
solutions downhole at various pressures to optimize the production
of the well.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more detailed description of the construction and operation
of the present invention, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which:
FIG. 1 illustrates in a general manner the uphole and downhole
equipment employed to carry out the various aspects and features of
the invention;
FIG. 2 is a side elevational view of a portion of two drill pipes
coupled together, and partially cross-sectioned to illustrate
thread engagement between the pipes and the coupling collar;
FIG. 3a is a cross-sectional view of the multi-conduit tubular,
taken along line 3--3 of FIG. 2;
FIG. 3b illustrates a cross-sectional view of an alternative
embodiment of a multi-conduit tubular illustrating circular,
peripheral conduits peripherally located about the central
conduit;
FIG. 3c is a cross-sectional view of yet another embodiment of a
tubular illustrating an outer pipe, an inner pipe forming a,
central conduit, and a plurality of other pipes forming
peripherally about the inner central pipe;
FIG. 3d is a cross-sectional view of still another embodiment of
the multi-conduit tubular illustrating a nest of individual
conduits occupying one conduit of the drill pipe of FIG. 3a;
FIG. 4 is a cross-sectional view of coupled multi-conduit tubulars,
taken through the coupling collar at line 4--4 of FIG. 2;
FIG. 5 is an isometric view of the tubular seal, and an
intermediate electrical connector fixed therein;
FIG. 6 is a cross-sectional view at the juncture of joined
tubulars, illustrating the seal and the intermediate electrical
connector;
FIG. 7 is a cross-sectional view of joined tubular conduits
carrying the electrical conductors, connectors and contacts;
FIGS. 8-10 are cross-sectional views taken along respective lines
8--8, 9--9 and 10--10 of FIG. 7;
FIG. 11 is an isometric exploded view of a portion of tubular end
sections to be joined with the seal;
FIG. 12 is front elevational view of an exemplary well drilling
derrick showing the gooseneck swivel and attached drill pipe
suspended therefrom;
FIG. 13 is a cross-sectional side view of the gooseneck swivel
illustrating the placement of the fluid and electrical commutators
on the quill section, together with the drill pipe drive
equipment;
FIG. 14 is an isometric view of the fluid distribution manifold and
the commutator shaft, with a portion of the manifold quarter
sectioned to illustrate the shaft inlet ports in fluid
communication with the annular grooves of the manifold;
FIG. 15 is a bottom view of the adaptor of FIG. 14 illustrating the
manner in which two or more pipe conduits may be commoned with a
single commutator shaft passage;
FIG. 16 is a side cross-sectional view of the fluid commutator
illustrating the connection of the manifold annular grooves to the
respective various shaft inlet ports, and the connection through
the shaft passages to the quill section;
FIG. 17 illustrates the electrical slip rings on the quill shaft,
with the corresponding brushes for communicating electrical signals
to or from the drill pipe wires;
FIG. 18 is a side plan view of a cross-over sub according to the
invention with sensor equipment attached thereto;
FIG. 19 illustrates a cross-over sub cross-sectioned to show a
blocked portion of a fluid conduit used to house downhole sensors
and telemetry equipment, with cross-over apertures around the
blocked conduit portion;
FIG. 20 illustrates in symbolic form the components of the annular
accumulator for applying a desired pressure to the drill fluid in
the annular area of the well;
FIG. 21 is a sectional plan view of the multi-conduit drill pipe
and attached bit using a high velocity fluid in some conduits for
cutting the formation and cleaning the drill bit, and illustrating
other low pressure fluids in other conduits for carrying cutting
chips upwardly around the annulus area;
FIG. 22 is another view similar to that of FIG. 21 wherein a gas is
forced down one drill pipe conduit, and vented downhole for
decreasing the hydrostatic pressure thereat;
FIG. 23 illustrates a drilling operation employing a liquid and gas
reverse circulation and coring technique;
FIG. 24 is a simplified illustration of a multi-conduit tubular
employed as a well casing;
FIG. 25 is a cross-sectional view of the multi-conduit well casing
taken along line 25--25 of FIG. 24;
FIG. 26 is an end view of the bottom of a well casing stub taken
along line 26--26 of FIG. 24;
FIG. 27 is a cross-sectional side view of the well casing stub
removed from the multi-conduit pump section;
FIG. 28 is a partial cross-sectional view of the terminal end of
the well casing stub, taken through the sensor chamber;
FIG. 29 is a fully assembled perspective of an improved drill pipe
coupling arrangement;
FIG. 30 is a partially assembled perspective of the coupling
arrangement of FIG. 29; and
FIG. 31 is an exploded partial cross-sectional view of the improved
coupling arrangement of FIG. 29.
DETAILED DESCRIPTION OF THE INVENTION
General Overview
Referring now to the figures, there is shown in FIG. 1 the general
aspects of the methods and apparatus according to the invention. As
shown, the invention includes the multi-conduit drill pipe
generally designated by the reference character 10 and is driven by
the multi-fluid gooseneck swivel 12. Drill bit 14 may be of the
many varieties available for eroding the subterranean formation 16
to bore a well.
Various downhole sensors, such as temperature sensor 18 or pH
sensor 20 may be employed within the drill bit 14 to gather
downhole data and transmit the same to surface monitor equipment 22
through drill pipe wires (not shown in FIG. 1). An electrical power
source 25 may also be provided to supply power to drill bit sensors
and control of downhole electrical tools, as needed.
A liquid pump 24 supplies high or low pressure fluid to a fluid
commutator 26 in the gooseneck swivel. Other similar pumps may also
be utilized so various fluids at the same or different pressures
can be pumped downhole to provide improved drilling techniques not
heretofore achieved. In a similar manner, a compressor 28 supplies
a gas, such as nitrogen, to the fluid commutator 26 for
distribution therein to desired conduits 30 of the drill pipe. When
the central conduit 32 of the drill pipe is utilized as the channel
through which the formation chips are carried in liquid or, gas
upwardly, such chips are carried by the gooseneck hose 34 to a
cyclone separator 36 which is effective to separate the chips from
the returned drilling fluid. Liquid pump 38 is also connected to
the gooseneck hose 34 to dump fluid from a source (not shown)
downwardly through the central conduit 32 to drill or alternatively
to counteract any undesired fluid flow in such conduit due to a
blow out in the well. Pump 38 may alternatively be used to pump
cement or another sealing material downhole to seal the well A
valve 40 is automatically closed when pump 38 is activated so that
the pumped material does not enter the separator 36.
Depending upon the method of drilling desired, kill line pump 42 is
provided to pump drill fluid down the annulus 44 of the well. An
annular accumulator 46 maintains a desired pressure on the annular
fluid in the well.
From the foregoing, it is evident that the invention provides
various options and alternatives to use in optimizing the drilling
operation based upon the existing conditions From the discussion
which follows, it will become even more evident that the present
invention provides an advance in the well drilling art not
heretofore recognized.
Multi-Conduit Drill Pipe
With reference now to FIG. 2 there is shown a coupled tubular
section, and particularly a drill pipe, forming a part of the drill
string, and more specifically the means by which end sections of
the drill pipe are joined. Shown in FIG. 2 is the aspect of the
drill pipe wherein a plurality of conduits, one shown as reference
character 30, are uniform throughout the drill pipe and thus
uniform across the tool joint 48 from one pipe 50 to another pipe
52 joined thereto Each such conduit 30 is rectilinear in nature,
despite the fact that the upset sections 54 and 56 of the drill
pipes shown in FIG. 2 are somewhat larger in diameter to satisfy
strength and sealing considerations.
The drill pipe 50 is more clearly shown by the cross-sectional view
of the multi-conduit tubular of FIG. 3a. It is of great practical
importance from the standpoint of versatility to provide many
conduits in the drill pipe, all of which are rectilinear throughout
the pipe and which can be interjoined to supply any desired number
of liquids or gases downhole, the liquids or gases being isolated
from one another and therefore capable of being supplied at
different pressures and quantities. To that end, the invention in
its preferred form is comprised of a drill pipe having an outer
sidewall 58 and an inner concentric sidewall 60 forming a central
conduit 62 through which, by choice and not by necessity, a
majority of fluid is pumped. Located between the inner sidewall 60
and outer sidewall 58, the various longitudinal conduits 30 are
defined in the nature of a longitudinal annular channel between the
inner and outer sidewalls, divided into the independent conduits 30
by radial dividers 64. Each conduit 30 thus has the general
cross-sectional configuration of a trapezoid with the arcuate sides
defining the parallel sides.
With this construction, it is highly advantageous to fabricate
drill pipes or well casings by extrusion methods out of aluminum
with steel upsets, or entirely of high grade steel. Conduit
configurations other than that shown in FIG. 3a may, of course, be
used to satisfy particular needs. For example, FIG. 3b illustrates
an alternative form of the multi-conduit tubular with an outer and
inner sidewall 66 and 68, the inner sidewall 68 again defining a
central conduit 62. In this form, however, a series of
cross-sectionally circular conduits 70 are spaced equal distances
peripherally about the central conduit 62 between the inner 68 and
outer 66 sidewalls. This form of the tubular may advantageously be
constructed by standing the pipe stock on end and drilling each
conduit vertically.
FIG. 3c shows yet another version of the multi-conduit tubular
similar to FIG. 3b, except constructed of a large pipe 72, the
exterior wall thereof forming the outer sidewall, and a smaller
pipe 74 forming the central conduit 62. Between the larger and
smaller pipes, 72 and 74, a plurality of other even smaller
diameter pipes 76 are peripherally located Each pipe of the FIG. 3c
is welded to an adjacent pipe at the pipe ends.
FIG. 3d depicts a modified version of the tubular of FIG. 3b. In
the tubular having perpheral circular conduits 70, there is
inserted a cylindrical multichannel insert 78, and fixed therein
such as by welding. The insert 78 includes a central axial channel
80 with a number of peripheral channels 82, all of which
effectively increase the number of conduits in the tubular, albeit
with decreased diameters.
It is seen, therefore, that an easily manufactured tubular has been
provided, with a plurality of independent conduits extending
uniformly throughout the length thereof It will be discussed at
length below the exact manner in which each such conduit may be
utilized to optimize the drilling or production operation.
Drill Pipe Coupling
With reference again to FIG. 2, the joining together of
multi-conduit tubulars used as drill pipes is accomplished by a
threaded coupling collar 84. When so joined, the pressure integrity
of each conduit is maintained by a seal 86, the details of which
will also be described below.
The end of drill pipe 50 is coupled to the end of drill pipe 52 by
a differential thread action between the external pipe threads 88
and 90 and the internal coupling collar threads 92 and 94.
Additionally, the ends of each drill pipe have threads 88 and 90
with a different pitch. For example, the end of drill pipe 50 shown
in FIG. 2 may have four threads 88 per inch (a pitch of 0.25) and
the end of pipe 52 shown may have five threads 90 per inch (a pitch
of 0.2). The coupling collar 84 is similarly threaded in that it
has coarse threads 92 for engaging the corresponding threads on
drill pipe end 50 and finer threads 94 (five threads per inch) at
the other collar end to engage with the respective fine threads of
drill pipe 52. It is to be noted that both the fine threads 94 and
90 and coarse threads 92 and 88 of both the coupling collar 84 and
drill pipes 50 and 52 are uniform diameter threads throughout the
respective threaded sections. However, the diameter of the drill
pipe end 50 at the coarse thread 88 is larger than the diameter of
the drill pipe end at the fine thread 90. The coupling collar 84
has similar thread diameters. The aspect of different thread
diameters permits the coupling collar 84 to be unscrewed from drill
pipe 50 onto drill pipe 52 wherein the coarse threads 92 of
coupling collar 84 do not become engaged with the fine threads 90
of drill pipe 52. In this manner, coupling collar 84 can be lowered
onto drill pipe 52 until it abuts stop flange 96.
Because the ends of the illustrated drill pipes include threads of
different pitch to provide differential coupling, the threads 88
and 90 are both either right-hand or left-hand threads. Preferably,
when pipes are coupled only by the coupling collar 84, the threads
will be in the direction wherein the rotary action of the drill
tends to tighten the coupling between drill pipes. Typically, the
threads are cut in a right-hand direction It is to be noted from
the foregoing that the other ends of drill pipes 50 and 52 have
thread pitches and diameters opposite that of the described pipe
ends. In other words, each pipe has coarse threads 88 at one end
and fine threads 90 at the other.
The coupling collar 84 is also of a larger diameter than the
coupled drill pipes so that any wear due to rotary action against
the bore hole wall will wear the collar 84 rather than the drill
pipes. To that end, the drill pipe coupling collar 84 is made
removable from drill pipe 52 by leaving a portion 98 on the
coupling collar end annularly and internally recessed so as not to
engage pipe threads 90. Alternatively, coupling collar internal
threads 94 could be extended to the end of the collar. Therefore,
when the coupling collar 84 has experienced undue wear, it can be
easily removed from drill pipe 52 and replaced. Normally, and for
reasons to be discussed below, drill pipes are usually stored or
shipped with their respective coupling collars 84 screwed fully
onto the drill pipe end in abutting relationship with stop flange
96.
With further reference to FIG. 2, and in keeping with the
invention, the ends of drill pipes 50 and 52 are meshed or
interlocked before being threadably coupled, to provide a means to
transfer the rotational drive torque from one drill pipe to the
next. In this manner, the rotational drive torque of the drill
string is not transferred by way of the threaded coupling collar
84. Therefore the threaded coupling collar 84 and pipe ends do not
need conventional tapered box and pin threaded tool joints to
transmit torque, which type of threads require expensive thread
dies.
FIG. 4 illustrates several drive lugs 100 received within
respective drive recesses 102 to provide meshing or interlocking
between coupled drill pipes. Reference to FIG. 11, which
illustrates multi-passageway drill pipes 103 and 105 with
electrical wires 110, clearly shows the drive lugs 100 on drill
pipe 105, and drive recesses 102 (in phanton lines) on the end of
drill pipe 103. The engagement between drill pipes 103 and 105 is
essentially an interleaving arrangement of drive lugs 100 and
recesses 102.
One lug 104 of drill pipe 105 and respective recess 106 of drill
pipe 103 are sized differently than the other drive lugs 100 and
drive recesses 102. Specifically, lug 104 is an index lug which,
together with index recess 106, provides a way in which one drill
pipe 105 may be joined to another 103 at a predetermined desired
arcuate or rotational alignment. According to the invention,
arcuate alignment between the drill pipes of a string is essential
as it is necessary to maintain alignment of the drill pipe conduits
throughout the drill string. In addition, it is even more important
to maintain a particular arcuate alignment of the drill string
pipes, such as 103 and 105, as one conduit, denoted as an
electrical conduit 108, carries electrical wires 110 as a medium
for supplying signals and power to downhole sensors, and signals
upwardly from the sensors or tools to surface equipment. The term
"signals" as used herein is intended to also encompass electrical
power, such as from alternating current (ac) or direct current (dc)
sources.
Therefore, it is seen that not only is it necessary to maintain
alignment between the fluid carrying conduits, but also to maintain
a particular alignment because one such conduit 108 carries
electrical wires. It is realized that in those applications where
it is desired to use every conduit of the drill pipe for fluids, it
is only necessary to provide drive lugs 100 and drive recesses 102
which maintain alignment of the conduits in general, but not for
particular conduits. It is also expected that in some instances
more than one conduit will carry electrical wires 110.
Electrical Conduit and Conductors
As noted above, the capability of a drilling operation to receive
instantaneous electrical signals from downhole sensors, such as 18
and 20, and operate in a closed loop manner can be advantageously
used to modify procedures for optimizing the operation. As noted in
FIGS. 7-10, an electrical conduit 108 of the drill pipe 103 carries
three electrical wires 110 formed together in a harness 112. The
harness 112 is preferably constructed with a durable cover, such as
Teflon or Kyner material so that any frictional movement between
the harness 112 and interior surface 114 of the conduit 108 during
drilling will not result in an electrical short circuit.
Each electrical wire 110 is terminated at the pipe end in a
connector block 116 having three wire terminals 118 and associated
pin contacts 120. Each electrical wire 110 is soldered to a
terminal 118 of its respective pin contact 120. The connector block
116 at each end of a drill pipe may be cemented or otherwise sealed
within the electrical conduit 108, or attached therein by other
suitable hardware (not shown).
Conduit Seal
In maintaining electrical continuity, as well as fluid continuity
between the respective conduits of one drill pipe to another a seal
86 is provided as shown in FIG. 5. The seal 86 is planar in nature
and cross-sectionally shaped similar to that of the illustrated
drill pipe. Particularly, the seal 86 of FIG. 5 is
cross-sectionally similar to the tubular embodiment of FIG. 3a, and
is constructed as a steel plate-like insert positioned between the
drill pipe ends. From the description which follows, it is well
within the ambit of those skilled in the art to construct conduit
seals for use with the tubulars of FIGS. 3b-3d. As shown in FIG. 5,
the seal 86 includes a central passage 122 and equidistantly spaced
individual peripheral passages 124 therearound. In one such
passage, an electrical socket-type intermediate connector 126 is
fixed, as shown in FIGS. 5-7. The intermediate connector 126 has
socket contacts 128 in each end thereof and into which the pin
contacts 120 of the pipe connector blocks 116 are frictionally
insertable to assure high quality electrical connections from drill
pipe to drill pipe. Moreover, the socket contacts 128 and pin
contacts 120 are plated with gold or other suitable material to
avoid the adverse oxidation effects prevalent in the well drilling
environment.
Intermediate connector 126, as with the drill pipe connector blocks
116, may be cemented or otherwise fixed into the seal plate 86.
Alternatively, the intermediate connector 126 may be provided with
mounting hardware for "floating" the connector within the seal 86.
This aspect allows the intermediate connector 126 a certain degree
of lateral movement within the seal 86 to accommodate small
dimensional differences between aligned drill pipes.
The provision of the seal 86, as well as the intermediate connector
126, is a departure from the customary drill pipe electrical
connections. The intermediate connector 126 is of great practical
advantage insofar as it permits both drill pipe ends to be fitted
with pin contact-type connector blocks 116. With this symmetrical
arrangement, the seal 86 has no right side up orientation, but
rather can be quickly installed with either end of the intermediate
connector 126 applied to either pipe end. In addition, the
manufacture of the exemplary drill pipe is simplified as only a pin
type connector block 116 need be installed in the electrical
conduit 108 of each pipe end.
Importantly, the seal 86 includes a sealing or gasket means in the
nature of a rubber or elastomer 130 encircling each of the
peripheral passages 124, including the central passage 122. In the
preferred form of the seal 86, a groove 132 is cut into each face
side of the seal 86, circumscribing the seal network around
adjacent peripheral and central passages 124 and 122. For ease of
construction of both the seal 86 and the elastomer gasket 130 the
groove 132 between adjacent passages is common thereby enabling the
elastomer gasket 130 to be made in a single piece. As noted in FIG.
6, when drill pipes 103 and 105 are interlocked together and firmly
coupled by the collar 84, the elastomer gasket 130 is squeezed
tightly within its groove 132 to form a high quality seal and
insure the pressure integrity between the respective fluid and
electrical conduits. With this type of seal, pressure differentials
upwardly of 50,000 p.s.i. may be sustained between adjacent
conduits. This seal arrangement represents an advance over the "O"
rings or chevron seals which can withstand differential pressures
upwardly of only about 7,500 p.s.i. For clarity, the electrical
connector blocks 116 in the electrical conduit ends of FIG. 6 have
been omitted.
An additional advantage of the drill pipe according to the
invention can be seen from FIG. 11 where the coupling collar 84, as
it is shown, is abutted against the stop flange 96 (not shown). The
coupling collar 84 is of such a length that when completely receded
on drill pipe 105 the terminal edge 134 thereof is at least flush
with the terminal edges 136 of the lugs so that such lugs cannot be
easily broken or damaged during storage or handling. In the same
vein, and to reduce vulnerability to damage, the terminal end of
the mating drill pipe 103 has a continuous cylindrical rim 138
therearound with the drive and index recesses 102 and 106 on the
inside surface thereof. Therefore, because of the continuous nature
of the rim 138 the terminal end of such drill pipe 105 is less
susceptible to damage. This is highly desirable as it can be seen
that an entire drill pipe can become unreliable if the lugs 100 and
104 or recesses 102 and 106 become excessively damaged.
With the foregoing in mind, it can be appreciated that many drill
pipes can be quickly and easily coupled together in a desired
arcuate alignment, with each fluid passage and electrical conduit
maintaining its integrity throughout the drill string.
Quill Section
Central to a principal feature of the invention, there is shown in
FIGS. 12 and 13 the surface apparatus of the drilling operation
utilized to communicate fluids and electrical signals to and from
the drill string. A hoist structure 140, suspended from a cable 142
connected to a derrick frame 144, holds the gooseneck swivel 12 in
suspension above the well head (not shown). Cable take-up and
release means (not shown) provide gross adjustments of the drill
string within the well bore, and thus gross adjustments of the
drill, bit weight. Torque arresting cables 148 prevent the goose
neck swivel 12 from rotating together with the topmost drill pipe
150.
Fine vertical adjustments of the gooseneck swivel 12 above the well
head are supplied by a pair of gas-over-oil hydraulic cylinders 152
supporting the quill 154 and washpipe 156 sections of the gooseneck
swivel 12 to the hoist structure 140. As noted in FIG. 13 the
hydraulic cylinders 152 each have a piston 158 located in a
partially fluid-filled cylinder 160 for maintaining a desired drill
bit weight. Each piston 158 includes circumferential seals 162
therearound to seal each such piston 158 against the inner wall of
the cylinder 160 and maintain the oil above the piston 158 separate
from atmospheric pressure below the piston 158. The upper portion
of each hydraulic cylinder 152 is coupled to a gas-over-oil source
(not shown) by hoses 164. It can be appreciated then that a high
gas pressure in the source results in a lightened drill bit weight.
A piston rod 166 of each hydraulic cylinder 152 is connected to the
hoist structure 140 by knuckle joints 168. Various fluids are
coupled to the gooseneck swivel 12 through high pressure hoses 170,
172 and 174 of FIG. 12. High pressure hose 176 atop the gooseneck
swivel allows fluid to be pumped down or extracted from the central
bore of the drill pipe 150.
In the description and drawings hereof, certain elements common to
drilling operations, such as the motor drive of the drill string,
the blow-out preventer at the well head, etc., have been omitted or
only briefly described as such elements do not contribute to the
invention and the existence and use thereof is well within the
competence of those skilled in the art.
The gooseneck swivel 12 of FIG. 13 is primarily comprised of a
quill section 154, which includes a quill shaft 178 connected at
its bottom end to the top-most drill pipe 150 with a tubular collar
180, a washpipe 156 and fluid commutator 182. An adaptor 184 is
effective in coupling the fluid commutator 182 to the quill shaft
178. The adaptor 184 as well as the quill shaft 178 have fluid
passages therein for communicating desired fluids to ones of the
drill pipe conduits. The manner in which various fluids are
commutated to desired drill pipe conduits will be treated more
fully below.
The gooseneck swivel 12 further includes an electrical commutator
186 for maintaining electrical connections to each of the drill
string wires 110 while the drill string is rotating. The quill
shaft 178 is driven by a gear 188 splined to the quill shaft 178
through a hydraulic or electric motor (not shown) The motor drive
unit is housed in a frame l90 through which the quill shaft 178
rotates in bearings 192, 194 and in thrust bearings l95. Suitable
oil seals are also provided for shaft 178.
Fluid Commutator
A simplified version of the fluid commutator 182 is shown in FIG.
14 wherein a commutator shaft 198 is rotatable within a fluid
manifold 198 and includes high pressure seals which will be
thoroughly discussed in connection with FIG. 16. Commutator shaft
196 includes a number of inlet ports 200 and 202 corresponding to
the different number of fluids desired to be pumped through the
various drill pipe conduits For exemplary purposes, only two fluid
sources are connected to the fluid commutator 182. For each inlet
port 200 and 202 there is a corresponding fluid passage 204 and 206
(shown in phantom) within the commutator shaft 196, each such
passage having an outlet on the bottom end of the commutator shaft
196. The commutator shaft 196 also has a central bore 208
therethrough and through which drill fluid or the like is
communicated to the central conduit 62 of the drill pipe 150.
Fluid Conduit Adaptor
The adaptor 184 provides an interface between the commutator shaft
196 and the quill shaft 178. The adaptor 184 is secured between the
commutator shaft 196 and quill shaft 178 by a pin 179 and recess
181 arrangement, and jam nuts 183. FIG. 14 illustrates a
perspective top view of the adaptor 184 having a central bore 210
in communication with the commutator shaft central bore 208, and
two channels 212 and 214 in communication with the commutator shaft
passages 204 and 206. FIG. 15 illustrates the configuration of the
bottom side of the adaptor 184. In the illustrated embodiment of
the quill section 154, it is desired to pump two different fluids
down various drill pipe conduits. Therefore, the bottom side of
adaptor 184 includes hollowed-out areas 216 and 214 around
respective passage channels 214 and 212. With this construction,
channel 214 is placed in fluid communication with three
corresponding quill shaft conduits 224, while channel 212 is placed
in fluid communication, for example, with four other corresponding
quill shaft conduits 222. The remaining conduit 226 in the quill
shaft 178 is plugged by the non-apertured area 220 on the adaptor
184.
Essentially then, inlet port 204 of the commutator shaft 196 is
capable of distributing one type of fluid to four adjacent quill
shaft conduits 222, and thus four corresponding drill pipe
conduits. Similarly, inlet port 202 is adapted to distribute
another drill fluid to three adjacent drill pipe conduits It should
be apparent now that a variety of adaptors may be provided at the
drill site for use in distributing fluids of a number of fluid
sources to a number of drill pipe conduits. This is accomplished by
providing different configurations of hollowed-out areas within or
on the bottom side of the adaptor 184.
Moreover, drilling operators may find from the teachings of the
present invention that more than two fluid sources at different
pressures can be used to optimize the drilling operation. In that
event, it will be apparent from the description the manner in which
a three or four inlet port commutator may be developed to
distribute a like number of different fluids to the drill pipe
conduits.
In FIGS. 14 and 16, and in more detail, the fluid manifold 198 has
input passageways 230 and 232 connected on the outside thereof to
respective fluid sources, and on the inside thereof to commutator
shaft inlet ports 200 and 202 by a pair of annular grooves 234 and
236. Inlet port 200 is therefore in continuous communication with
fluid as it rotates within its respective annular groove 234.
Similarly, inlet port 202 is in continuous communication with
another fluid by way of its annular groove 236.
Because the fluid commutator 182 is subjected to fluid pressures
limited only to the strength of connecting hoses 170-174 (FIG. 12),
a special arrangement must be provided for maintaining a seal
between the annular grooves 234 and 236 and the rotating commutator
shaft 196. The high pressure sealing arrangement more clearly
depicted in FIG. 16 is utilized in the fluid commutator 182 of the
gooseneck swivel 12 so that the various high pressure fluids can be
used to facilitate the downhole drilling operation. The exterior
surface of the commutator shaft 196 is faced with a ceramic
material 240 which provides a durable and long lasting bearing
surface for the shaft 196 within the fluid manifold 198.
Around each annular groove 234 and 236 are high pressure seal rings
242 which seal the fluid manifold 198 to the ceramic facing 240 of
the commutator shaft 196. Low pressure seals 243 are disposed on
opposing ends of shaft 196. To counteract the high pressure exerted
on one side of a high pressure seal 242, another high pressure
control fluid is applied to the opposite side of the high pressure
seal 242. In this manner, the differential pressure on each side of
the high pressure seal 242 is reduced and the possibility of
pressure blow outs is also reduced. Accordingly, high pressure seal
fluid inlet ports 244 have been provided, as shown in FIG. 16, for
supplying a fluid under high pressure to one side of each high
pressure seal ring 242, to equalize the pressure on the other side
of the high pressure seal rings 242 resulting from high pressure
drill fluids pumped down the drill pipe conduits. A number of low
pressure seal fluid outlet ports 246 have been provided for
returning the leakage pressure control fluid which equalizes the
high pressure seals 242 back to a reservoir (not shown).
Without repeating the details of high pressure sealing, the central
bore 208 in the commutator shaft 196 may be sealed by the same high
pressure technique discussed above.
It should be understood that the invention, according to the
foregoing description affords a drilling operator the ability to
selectively inject a different number of extremely high
differential pressure fluids into any number of different drill
pipe conduits and apply the fluids to downhole equipment to, for
example, clean or cool drill bits, aerate drilling fluid or aid the
cavitation or erosion of the formation, or effect each operation
simultaneously.
Electrical Commutator
An electrical commutator, generally designated 186 in FIG. 17
provides continuity of electrical connections between the rotating
wires 110 within the drill pipe, and the surface monitor equipment
22. The drill pipe electrical wires 110 are coupled from the
topmost drill pipe 150 and through a corresponding connector (not
shown) at the bottom of the quill shaft 178. Electrical wires
within the quill shaft 178 are also provided with a connector 250
at their top end and are finally connected to connector 252 of FIG.
17. For exemplary purposes here, four electrical wires are carried
through the drill pipes 150. Four corresponding conductors 254,
256, 258 and 260 are fastened to a terminal block 262. From the
terminal block 262 each of the four conductors are connected to a
respective slip ring 264, 266, 268 and 270. The slip rings are
constructed of brass, or other suitable electrically conducting
material, are fixed to the quill shaft 178 and thus rotate with
such shaft.
The electrical signals carried by the respective wires 110 from the
downhole sensors are thus present on each of the respective
rotating slip rings 264-270. Four brushes 272, 274, 276 and 278 are
held in compression against the respective slip rings to provide a
reliable electrical contact therewith. The brushes are stationary
and are pressed against the respective slip rings by brush holders,
such as shown by reference character 280. The brush holders are
fixed in a block 282 which, in turn, is fastened to the gooseneck
swivel frame. Within the block 282, individual conductors such as
284 are connected to the individual brushes 278 to carry the
electrical signals to the monitor equipment. The electrical
commutator 186 is covered by a protective cover (not shown) to
avoid exposure of the slip rings to the harsh well drilling
environment.
It is seen, therefore, that the invention provides for a number of
electrical wires 110 to be routed through the drill string to
downhole apparatus. The electrical signals from the downhole
apparatus are instantly available to the surface monitor equipment
22 and can thus be acted upon accordingly.
Cross-Over Sub
With regard to a further feature of the invention there is
illustrated in FIGS. 18 and 19 a cross-over sub 286 which is
ideally suited to operate in conjunction with the improved drill
pipe to expand its versatility. The cross-over sub 286 is a short
section of drill pipe with collar couplings as described above, and
with a provision for sensor equipment generally designated 288.
Specifically shown are three sensors, a pressure sensor 290, a pH
sensor 20 and a temperature sensor 18.
Each sensor is electrically operated and is thus connected to
telemetry or transducer apparatus 292 for converting the sensor
physical inputs to electrical signals for transmission to the
surface monitor equipment. As shown, the telemetry apparatus 292 is
wired to the electrical wire harness 112 which extends upwardly in
the drill string to the slip rings. The wire harness 112 is
disposed in the electrical conduit 108.
Because there may be insufficient room in the electrical conduit
108 for sensors and telemetry equipment, a part of a fluid conduit
294 has been blocked off by separators 296 and 298. A duct 297
connects the blocked off portion 303 with the electrical conduit
108 so that electrical wires 110 can be routed from the electrical
conduit 108 to the telemetry equipment 292 located in the blocked
off portion 303. An access and mounting plate 300 mounts into an
access opening 302 in the blocked off portion 303 of the fluid
conduit 294. The mounting plate 300, along with a gasket 304 is
secured by screws 306 to the wall of the cross-over sub. A
conventional rubber gasket 304 is sufficient as the blocked conduit
303 is not subjected to extreme pressures.
A plurality of cross-over openings 308 are formed into conduit
divider 310 for allowing the fluid from the upper part of conduit
294 to be rerouted through fluid conduit 312, around blocked off
conduit portion 303, and back into the lower part of conduit
294.
In order to reduce the hydrostatic head at the bore site it is
customary to aerate the drill fluid. Accordingly, the exemplary
cross-over sub 286 is provided with external aeration apertures 314
for aerating the drill fluid in the annulus 44 of the wellbore, and
internal aeration apertures 316 for aerating the drill fluid in the
central conduit 318. As noted from FIG. 19, to provide internal and
external aeration, fluid conduits 320 and 322 which are connected
to the respective central conduit 318 and the well bore annulus by
the noted apertures, are provided with a pressurized gas such a
nitrogen It should be apparent that a single cross-over sub 286 may
not normally include all the features of the illustrated sub. Also,
specialized drill pipes of the above described type may be fitted
with one or more of the features described in connection with the
cross-over sub 286.
Collets 324 and 326 provide protection for the sensors against
damage either during storage or when used downhole. The collet 324
also acts as a stop for the coupling collar 84.
The cross-over sub 286 therefore provides a means in which to mount
environmental formation sensors in the drill string, while yet
permitting fluid flow in each fluid conduit. It is realized that
when using the cross-over sub 286 the same fluid should be pumped
into conduits 294 and 312 since such conduits are placed in fluid
communication by the openings 308.
Annular Accumulator
An annular accumulator 46 is shown in FIG. 20. This apparatus
enables selective mechanical adjustments in the wellbore
hydrostatic head for improved wellbore integrity and to provide the
ability to make continuing adjustments as differing geopressures
are encountered. Specifically, this apparatus prevents those events
from occurring which can lead to a disastrous and costly well
blowout. Normally, an excessive building of pressure downhole is
counteracted by increasing the density of the drill mud in the
annulus 44 of the wellbore. In the event pressure builds up too
quickly, or if the drilling operators are inattentive to such
buildup, the drill mud density cannot be changed quickly enough to
avert a blowout.
The annular accumulator 46 addresses this very problem by providing
the capability of quickly changing the effective density of the
drill mud 327 by applying pressure thereto in the wellbore annulus
44. The annular accumulator 46 comprises a reservoir 328 connected
to the wellbore annulus 44 through appropriate plumbing 330. A
rotating head 331 forms an annular seal around the drill pipe to
provide a closed system.
The reservoir 328 includes a flexible diaphragm 332 which separates
the drill mud 327 from the pressurized gas 334 thereabove. It is
seen that with an increase in the gas pressure on the diaphragm
332, and thus on the drill and mud 327, the effective density of
such mud is increased. A gas pump 336 compresses a gas into a
relatively large volume supply tank 338 so that on demand the gas
pressure 334 in the accumulator reservoir 328 can be quickly
increased. A regulator 340 is adjustable and permits a regulation
of the gas 334 between the supply tank 338 and the accumulator
reservoir 328. Thus, on an indication of a pressure adjustment
requirement, the regulator 340 may be opened to increase the gas
pressure on the drill mud 327, and thus increase its effective
density.
According to an important aspect of the invention, the regulator
340 can be automatically adjustable, and connected to a surface
pressure monitor 342 for automatically adjusting the accumulator
reservoir 328 pressure based upon instantaneous downhole pressure
changes sensed by the pressure sensor 290. Therefore, through the
closed loop system imminent blowout catastrophes can be detected
early and avoided with the present invention. In addition, the
pressure monitor 342 can be utilized to initiate operation of pump
42 in order to maintain the downhole fluid levels at the desired
magnitude.
Improved Drilling Method
Having described the apparatus of the invention in what is
conceived to be the most practical and preferred embodiment, an
improved method of drilling, using such apparatus will now be
described. With this in mind, attention should be directed to FIGS.
21-23 where there is illustrated an enlarged drill pipe and
wellbore utilizing the various features of the invention.
In FIG. 21 there is shown a method of drilling using a liquid 344,
such as a drill fluid of a first density, pumped downhole in one or
more conduits 346 to facilitate the removal of formation chips 347
from the drill bit 348 area through high velocity jetting action.
The chips 347 suspended in the drill mud are carried upwardly in
the wellbore annulus 44 to the surface. The drill fluid 344 is also
pumped downhole in other conduits 352. In these conduits 352 the
drill fluid 344 is under considerably more pressure than that in
conduit 346 and is directed into the drill bit boring path 354 to
erode the formation and/or quickly remove the chips 347 out of the
boring path 354. Drill fluid 356 of a second density may be pumped
down the drill pipe central conduit 358 in large quantities, and at
the drill bit area 348 be mixed with the drill fluid 344, the
combination of which is forced upwardly in the wellbore annulus 44
carrying formation chips 347.
Accordingly, with the provision of the multi-conduit drill pipe
drilling operators are able, for the first time, to independently
and simultaneously pump downhole a drill fluid at a pressure
adequate to clean the cuttings from the drill bit and drill path,
pump a drill fluid at an extremely high pressure to erode the
formation, and pump yet another drill fluid at a large volume and
low pressure downhole to force cutting chips upwardly in the well
bore annulus.
The drilling operation represented in FIG. 22 is similar to that of
FIG. 21, but in addition includes one type of cross-over sub 360 in
which a pressurized gas 362 is pumped through external aeration
apertures 314 into the wellbore annulus 44 to aerate the mixed
density drill fluid thereby reducing its effective density. Stated
in another way, this aeration reduces the hydrostatic pressure in
the drill bit area 348. It can be appreciated then that between the
aeration in this example and the pressure exerted on the drill
fluid by the annular accumulator 46, the density of the drill fluid
can be quickly changed, and changed within a wide range.
FIG. 23 illustrates a coring operation wherein the high pressure
drill fluid 344 is applied to the drill bit area 348 through
certain conduits 346 and 352 and through jets (not shown), and
reverse circulated upwardly with the formation chips 347 through
the central conduit 358 of the drill pipe. In addition, reverse
circulation of the drill fluid 344 is enhanced by aeration in the
nature of compressed gas 362 pumped down fluid conduit 364 and
expelled into the central conduit 358 through internal aeration
apertures 316. Fluids can alternatively be injected into the outer
annulus of the drill pipe to properly condition the outer area.
It will also be understood that the configuration shown in FIG. 23
could be modified by utilization of the drill bit 14 of FIG. 21. In
this embodiment, the chip size will be reduced in order to enhance
full pneumatic transfer uphole.
From the foregoing, an improved well drilling apparatus and method
have been described. It can be appreciated that many of the various
aspects and features described above may be combined to further
enhance the drilling operation. For example, sensors other than
those disclosed can be mounted to the drill pipe to sense desired
formation data, much like the pressure sensor as noted above, and
be coupled to surface equipment to modify the drilling operation.
Such a closed loop system eliminates the intervention by operators
who may delay in acting upon the information, or not act at all.
Moreover, such a closed loop operation permits continuous
adjustments, of whatever magnitude, on the drilling operation with
the aim of optimizing the system efficiency
In an important aspect of the invention, the three functions of (1)
maintaining chemical and pressure integrity in the wellbore, (2)
circulation of cuttings out of the hole, and (3) assisting in the
cutting or erosion of the formation are able to be isolated and
therefore independently manipulated and controlled. The present
invention can thus use multiple and separate fluids, and
combinations thereof, to perform the three functions noted above.
This ability contrasts with the prior art wherein the three
above-noted functions were not able to be isolated and
independently manipulated or controlled.
Multi-Conduit Well Casing
Another principal aim of the invention is the provision of a well
casing with multiple conduits. The provision of a multi-conduit
well casing engenders a number of advantages as broad in scope as
that discussed above in connection with drill pipes.
It is appreciated by those familiar with the art that even after a
well has reached its production stage, a highly developed well
management schedule must be performed to assure that the well is
producing at its peak efficiency. The overall production management
of a well has heretofore been limited by the amount of downhole
information which can be gathered to either change the downhole
conditions to improve efficiency, or to change the surface pumping
operation in an attempt to improve the overall efficiency. Much
like the well drilling operation described above, with the
provision of the transmission of multiple fluids and electrical
signals, a highly efficient closed loop well production system can
also be achieved.
Among those items which must be addressed in a highly developed
production system are downhole conditions relating to zone
pressures and temperatures, flow rates, fluid viscosities and
densities, fluid pH levels, etc. It is advantageous to monitor
these parameters, and others, to control surface operations to, for
example, control the pressure of a gas forced downhole to decrease
the hydrostatic pressure thereat and inject solvents or solutions
downhole to break up the oil or adjust the pH level. Other
solutions may be simultaneously pumped downhole to further affect
the formation so that additional oil, or the like, is released
Other applications may require the injection of an alcohol
solution, or an anti-freeze agent, downhole to prevent undesirable
low temperature conditions due to the temperature lowering affect
of a gas flow.
From the foregoing, it can be seen that it is highly desirable to
have available the ability to simultaneously pump a number of
liquids downhole and monitor a plurality of downhole parameters. In
accordance with the invention, FIGS. 24 and 25 are illustrative of
a multi-conduit well casing 366 which can be employed to overcome
the shortcomings attendant with the well casings heretofore known.
The general characteristics of the well casing 366, as well as the
arrangement for coupling casings together to form a string, are the
same as that described above in connection with drill pipes.
Because various conduits of the casing 366 may also carry high
pressure fluids, a seal 86 (FIG. 27) which is comparable to the
seal of FIG. 5, assures the pressure integrity between the conduits
of the well casing 366.
In particular, FIG. 25 illustrates a cross-sectional configuration
of the well casing 366, including a central bore 370, a plurality
of fluid conduits 372, and electrical conduit 374 carrying a
plurality of telemetry wires 376. Each of the telemetry wires 376
is has a connector at the electrical conduit ends, and joined
through the intermediate connector 126 of the seal 86 to
corresponding telemetry wires of other well casing sections of the
string. It should be noted that the multi-conduit well casing 366
of FIG. 25 is generally the same as the multi-conduit drill pipe of
FIG. 3b, except the well casing tubular is somewhat larger in
cross-section to fit within the well bore. In addition, the central
bore 370 is somewhat larger in diameter to accommodate the larger
volume of production fluid pumped upwardly.
With reference to FIG. 24, the topmost well casing 366 is coupled
by a collar 84 to well head cap depicted by reference character
378. A well head cap stub 380 is similar in cross-section to the
well casing 366, and includes provisions for a seal 86 (not shown),
as well as the index and drive lugs and recesses discussed above in
connection with FIG. 11. The well head cap 378 includes a plurality
of channels 382 (shown in phantom) therethrough connecting each
well casing conduit 372 and 374 to a respective fluid or solution
supply, and monitor and control panel 394. In the illustrated
embodiment of the invention, each of the seven fluid conduits 372
of the well casing 366 is connectable through a fluid distributor
386 to each of the fluid sources indicated by 388. High pressure
hoses, such as that shown by hose 384 connect each of the well head
cap channels 382 to an outlet 390 of the fluid distributor 386.
The telemetry wires 376 in the electrical conduit 374 are coupled
through the well head cap electrical conduit 392 (shown in phantom)
to a monitor and control panel 394. The monitor and control panel
394 may include meters, alarms, graphical monitors or amplifiers to
transform the telemetry signals into other signals to, for example
operate a bank of solenoid-equipped valves (generally designated
396) such as used in connection with the fluid manifold 397 of the
fluid distributor 386.
In this manner, a closed loop system is provided in which the
surface equipment may be automatically operated in response to
changing downhole parameters sensed by sensors. For example, in
response to an indication of an increased viscosity of the
production fluid downhole, as sensed by a sensor 424 (to be
discussed in more detail below), the monitor and control panel 394
will process the electrical indication thereof and cause one of the
solenoid operated valves 396 to be operated to thereby connect an
alcohol fluid source through the fluid distributor 386 to one or
more of the well casing fluid conduits 372 such that the viscosity
of the production fluid is changed. Moreover, as the viscosity
sensor transmits to the monitor and control panel 394 the
instantaneous viscosity of the downhole production fluid, one or
more other solenoid operated valves 396 may be operated or released
to increase the amount of fluid by routing such fluid to other
fluid conduits 372, or decrease the amount of fluid pumped downhole
by decreasing the number of fluid conduits 372 through which such
solvent is pumped.
While the solenoid operated relays 396 and the manifold arrangement
have been shown in general, specific arrangements may be devised by
those familiar with the art.
A manual push button panel 400 is also provided for manually
operating the solenoid operated valves 396 so that any one of the
fluids can be pumped through any one or more of the well casing
fluid conduits 372.
The well head cap 378 also includes a central bore (not shown)
through which a pump shaft 402 extends downhole to provide the
pumping action by which the production fluid is elevated to the
surface.
The bottom-most part of the well casing comprises a well casing
stub 404 which provides an outlet for each of the fluid conduits
372, as well as the electrical telemetry sensors. The well casing
stub 404 is threadably coupled to a special multi-conduit tubular
406 which houses a conventional reciprocating plunger to elevate
the production fluid to the surface.
FIGS. 26 and 27 depict the various features of the well casing stub
404. As viewed from below, the well casing stub 404 (FIG. 26)
includes a mesh screen 408 covering the central bore 370, and is of
a desired grade so as to prevent sand particles, and the like, from
entering into the pump section 406. The mesh screen 408 is
constructed of stainless steel, or other similar durable material
resistant to corrosion, and includes holes around its peripheral
edge aligned with the fluid conduits 372 so that the fluid may be
jetted out of the bottom of the well case stub 404 unrestricted by
the mesh screen 408. The mesh screen 408 is retained within the
well casing stub 404 by being clamped between a shoulder 410 of
collar 412 and the conduit terminal end 414. The conduit terminal
end 414 of the stub 404 includes plural fluid conduits 372, a
central bore 370 and an electrical conduit 374 all in registry,
through the multi-conduit pump section 406, with corresponding
conduits of the multi-conduit well casing 366. In addition, the
well casing stub 404 includes drive and index lugs matable with
respective drive and index recesses on the multi-conduit pump
section 406. As noted above, seal 86 assures the pressure integrity
between the corresponding conduits of the well casing stub 404 and
the multi-conduit pump section 406.
As noted in FIG. 26, each fluid conduit opens into the bottom of
the well bore through nozzle apertures 416. As noted by the
drawing, nozzle apertures of different diameters may be provided
for different needs.
FIG. 27 further illustrates the telemetry wires 376 in the well
casing stub 404 and in the multi-conduit pump section 406.
Electrical conduit connector 418, seal intermediate connector 126
and well casing stub connector 420 provide continuity of the
telemetry wires 376 to the sensor chamber 422. The sensor chamber
422 within the well casing stub 404 is shown in greater detail in
FIG. 28. In FIG. 26 a plurality of sensors, one of which is shown
as reference character 424, are provided in the terminal end of the
sensor chamber 422. The sensor chamber 422 includes a number of
threaded inlets 426 into which an externally threaded sensor 424 is
secured This arrangement is much like a threaded fuse in an
electrical junction box, with the exception that there is provided
a gasket 428 which prevents fluid from leaking into the sensor
chamber 422. Spring loaded sensor contacts 430 provide continuity
from the sensor element 424 to the telemetry wires 376.
This construction is highly advantageous as a number of sensor
elements 424 can be preselected and secured within the well casing
stub 404 to sense particular downhole parameters which are expected
to be critical to production of the particular type of well.
Amplifiers and other detector equipment in the monitor and control
panel 394 may be wired according to the type of sensors 424
installed in the well casing stub 404 so that the particular
parameters sensed can be transposed into usable indications of such
parameters. In addition, should it be desired to employ more sensor
elements 424 and telemetry wires 376 than can be accommodated by a
single electrical conduit 374, other fluid conduits may be fitted
with telemetry wires and corresponding connectors to provide an
additional capacity for sensor equipment.
With regard to FIG. 27 the collar 412 secures the conduit terminal
end 414 to the multi-conduit pump section 406 by the corresponding
internal and external threads. The multi-conduit pump section 406
has a central bore 432 which serves as the cylinder in which the
pump plunger 434 is reciprocally moved to force production fluid
upwardly. The pump plunger 434 includes conventional
circumferential seals 436 for preventing a fluid seal above and
below the pump plunger 434. On the downstroke of the pump plunger
434 production fluid is forced upwardly through passage 440,
through open check valve 438 and to the top side of the pump
plunger 434. On the upstroke of the plunger 434, the check valve
438 closes and production fluid is forced upwardly to surface
storage tanks (not shown).
Multi-Conduit Drill Pipe and Coupler
FIG. 29 shows a portion of a drill string including the bottom end
of an upper drill pipe 596, a top end of a lower drill pipe 598,
and a fully assembled coupling assembly generally identified by
reference numeral 600. Of course, a typical drill string would
include many more drill pipes and couplings. The coupling assembly
600 comprises a collar 638, a seal subassembly 644, and a lift
subassembly 682 for coupling the multi-conduit drill pipes 596 and
598 of the invention together. To be described in more detail
below, the bottom end of each drill pipe includes a hole 700 for
equalizing internal and external fluid pressures between the outer
casing of the drill pipe.
FIG. 30 shows the drill pipe ends and coupling 600 separated into
its two main components: a first end assembly 610 and a second end
assembly 612. FIG. 30 illustrates the drill pipes as they would
appear fully assembled and ready for use at the drilling site.
FIGS. 29 and 30 are of a reduced scale compared to FIG. 31 for
convenience of illustration only.
FIG. 31 shows the details of the multi-conduit drill pipes of the
invention and the coupling 600 broken down into their individual
subassemblies. Each drill pipe 596 and 598 includes a tubular outer
casing 614 and 616. As can be further seen by FIG. 31, the outer
casing 614 of the upper drill pipe 596 has external threads 618 on
its bottom end 622. The outer casing 616 of the lower drill pipe
598 has external threads 620 on its top end 624. As can be
appreciated, the two drill pipes 596 and 598 shown with the
illustrated top and bottom ends 622 and 624 are identical in
construction.
Enclosed by the outer casing 614 of the upper drill pipe 596 is a
plurality of radial tubes 626 and a central conduit 628. The radial
tubes 626 are arranged peripherally around the central conduit 628.
A plurality of similar radial tubes 630 and central conduit 632 can
also be seen to be enclosed by and extend from outer casing 616 of
the lower drill pipe 598. The bottom ends of the radial tubes 626
and the central conduit 628 have polished unthreaded ends, whereas
the top ends of the radial tubes 630 and the central conduit 632
have external threads 634 and 636, respectively. Central conduits
628 and 632 are constructed longer than radial tubes 626 and 630.
Also, the radial tubes 626 and 630 are constructed longer than the
outer casings 614 and 616.
A collar 638 is designed to be secured over the outer casing 614 by
threading the same onto the lower end 622 thereof employing outer
casing threads 618 and collar internal threads 640. The collar 638
also has reverse internal threads 642 for threadably securing the
collar to the seal subassembly 644 with reverse outer threads 646
of the seal subassembly 644. Seal subassembly 644 also has external
threads 648 on an opposite end from that on which threads 646 are
formed. Threads 648 are right-hand and of the self-sealing
type.
The seal subassembly 644 has an outer diameter and an inner
diameter defining a thick side wall 650 and a central bore 654. The
central bore 654 is constructed to receive therein the central
conduit 628 of the upper drill pipe 596 and the central conduit 632
of the lower drill pipe 598. A plurality of radially arranged
channels 656 are formed axially within the thick sidewall 650. The
channels 656 are radially arranged and spaced apart for receiving
therein the upper and lower radial tubes 626 and 630.
The seal subassembly 644 has internal threads 658 formed within the
central bore 654, as well as internal threads 660 formed within
radial channels 656. Neither the central bore 654 nor the radial
channels 656 are threaded at the opposite end.
Each radial channel 656 has an enlarged diameter portion 662
constructed to allow the lower ends of the radial tubes 626 to be
freely slidably received therein. The channel section 663 connects
the sealed channel end with the threaded channel end to provide an
individual fluid passage through the seal subassembly 644. Enlarged
portion 662 is formed so as to allow the radial tubes 626 to
telescopically slide axially within the seal subassembly 644 in
response to any tensile forces on outer casing 614 which may tend
to lengthen such outer casing. The central bore 654 of the seal
subassembly has an enlarged diameter portion 664, similar to the
enlarged diameter portions 662 of the radial channels 656, for
slidably receiving therein the central conduit 628 to allow for
axial movement thereof in response to the noted tensile forces on
outer casing 614.
Each end of the radial channels 656 are provided with internal
annular grooves 666 and 668 for receiving therein T-ring type seals
(not shown). The central bore 654 is similarly provided with
internal annular groove 670 and 672 for also receiving T-ring
seals, one of which is shown as seal 674 in groove 670. All T-ring
seals are provided with back-up rings, for example, as shown by
ring 676 on T-ring 674, to prevent movement of the T-ring seals
during any telescopic axial movement of the central conduit 628 or
radial tubes 626 with respect to the seal subassembly 644. The
radial channels 656 and the central bore 654 are provided with
sealing surfaces 678 and 680, respectively, so that when tensile
forces are applied to the outer casings 614 and 616, the radial
tubes 626 and the central conduit 628 will maintain in sealing
contact with their respective T-ring seals. The sealing surfaces
678 and 680 are constructed with a reduced diameter, with respect
to the enlarged sections 662 and 664, for engaging the respective
radial tubulars 626 or central conduit 628 in response to radial
expansion thereof because of high pressure fluids carried therein
The sealing surfaces 678 and 680 function to contain the T-ring
seals and prevent flowing thereof when the radial tubulars 626 or
the central conduit 628 expands radially and telescopically moves
with respect to the T-ring seals.
Importantly, that part of the outer surfaces of the radial tubes
626 and the central conduit 628 which engages with the T-ring seals
are polished or otherwise made smooth so as to provide a high
quality seal with the T-rings. In like manner, the sealing surfaces
678 and 680 are precision machined or otherwise made smooth to
prevent galling thereof, or galling of the radial tubes 626 or
central conduit 628, as the parts move axially with respect to each
other. This is essential when the radial tubes 626 and central
conduit 628 carry high pressure fluids an telescopically slide
within the T-ring seals as the drill string extends many feet into
the earth and becomes elongated due to its own weight. Portions of
the threaded ends of the radial tubes 630 and the central conduit
632 are comparably polished to provide a sealing surface with the
T-rings located within the annular grooves formed at the bottom of
the seal subassembly 644. All T-ring seals and back-up rings are of
a type well known in the art, as for example those manufactured by
Parker Seal Group of Lexington, Ky.
The lift subassembly 682 is constructed for threadable attachment
of the seal subassembly 644 to top end of the outer casing 616 of
the lower drill pipe 598. The lift subassembly 682 has an annular
recess 684 formed around its outer surface to facilitate attachment
of the top drill pipe 596 to the bottom drill pipe 598 (FIG. 30).
Plural annular recesses can be employed to assist in the automatic
indexing and positioning of the drill string when adding drill
pipes thereto. The lift subassembly 682 has internal threads 686
for attachment to the seal subassembly 644 and other internal
threads 688 for attachment to the top part of the outer casing 616
of the lower drill pipe 598. Internal threads 686 and 688 are of
the self-sealing type.
In accordance with an important feature of the invention, the
recessed area 684 and the lower end edge 689 of the lift
subassembly 682 provide particular areas of the lower drill pipe
598 which can be engaged by automated suspension hoisting equipment
to repeatedly position the drill string at a predetermined vertical
position In this manner, when it is necessary to attach an
additional section of drill pipe to the drill string, automated
equipment can be utilized to position the drill string, align the
added drill pipe thereover, and fasten the two together. Drill
string handling equipment, such as a spider, can be used to grasp
the drill pipe casing 616 and prevent slipping thereof due to
engagement with the lift subassembly end edge 689. When multiple
annular recesses 684 are employed, one such recess can be used for
gripping by the spider equipment. This feature permits automated
drilling operations so that risk of harm to personnel is reduced,
as well as provide an increased pipe handling efficiency.
In accordance with another feature of the invention, one or more of
the radial tubes 626 may be designated for receiving electrical
wiring. As can best be seen in FIG. 30, radial tube 690 is of a
smaller diameter than the other radial tubes 626. Radial tube 690
may be used for housing electrical wires or cables, and by its
smaller diameter may also serve as a means for indexing the
connection of one drill pipe to another. Electrical connectors (not
shown) of the plug and socket type may be used to facilitate the
electrical connections for joining the wires between joined drill
pipes.
The outer casing 614 is pierced to form a fluid port 700, shown in
FIG. 29. This allows equalization of internal and external fluid
pressure of the casing 614. Each drill pipe outer casing is
comparably constructed for such pressure equalization. With
pressure equalization, the outer casings 614 and 616, collar 638,
seal subassembly 644 and lift subassembly 682 can be constructed of
a high strength steel and subjected only to tensile and torque
forces. By utilizing the equalization ports, the outer casings 614
and 616 do not need to also withstand compression and burst forces
Steel having a tensile strength in the range of 100,000 pounds is
suitable for use in constructing the drill pipes of the invention.
On the other hand, the radial tubes 626 and 630 and the central
conduits 628 and 632 need be constructed so as to withstand only
compression and burst pressure forces. Because the radial tubes 626
and the central conduit 628 are constructed for telescopic movement
within the respective T-ring seals, they thus sustain no torsional
or tension forces. Accordingly, the drill pipe of the invention is
constructed with separate elements so that one element sustains
torsion and tension loads, while the other element sustains
compression and burst loads. Each such element can thus be
constructed with reduced strength, as each such element does not
have to withstand all four forces. The hole 700 located at the
bottom of each drill pipe facilitates the use of blowout preventers
for capping the drill pipe as well as the well annulus.
In assembling the drill pipes of the invention, the central conduit
632 is first secured to the internal threaded part 658 of the seal
subassembly 644. Next, the radial tubulars 630 are threaded into
the corresponding threaded holes 656 formed within the seal
subassembly thick sidewall 650. When indexing is desired, or when
using different sized radial tubulars, the proper sized tubulars
are used to provide a desired angular indexing of the drill pipe.
Once all tubulars are secured to the seal subassembly 644, the lift
subassembly is threadably secured to the seal subassembly 644. The
outer casing 616 of the lower drill pipe 598 is then slid over the
radial tubulars 630 and threadably secured to the lift subassembly
682. This procedure completes the assembly of the top part of the
lower drill pipe 598 as noted in FIG. 30.
When coupling drill pipes together, the central conduit 628 of the
upper drill pipe 596 is inserted into central bore 654 of the seal
subassembly 644, and the radial tubes 626 are rotated to properly
index with the matching radial tubulars 630 of the lower drill pipe
598. The collar 638 is then threadably attached to the seal
subassembly 644. Due to the reverse design of threads 642 and 646,
the turning of collar 638 forces outer casing 614 toward the seal
subassembly 644, thus fully inserting the radial tubes 626 and the
central conduit 628 into the corresponding channels and bore of the
seal subassembly 644. As shown in FIG. 29 the drill pipes are now
fully assembled.
In summary, the foregoing illustrates the advantages presented by a
multi-conduit tubular employed as a drill pipe or as a well casing.
Because of the plurality of conduits provided a variety of access
channels are available at the bottom of the bore hole, whereby a
multiplicity of downhole parameters may be sensed, tools operated
and, through the various fluid conduits, the overall drilling and
production of the well can be managed to a higher degree of
efficiency.
While the preferred embodiments of the methods and apparatus have
been disclosed with reference to specific constructions of the
tubulars, conduits, coupling and the like, it is to be understood
that many changes in detail may be made as a matter of engineering
choices without departing from the scope of the invention as
defined by the appended claims. Indeed, those skilled in the art
may prefer, for example, to embody the cross-over sub features
directly into a drill pipe, seal assembly or drill bit, and in
light of the invention they will find it easy to implement that
choice. Also, it is not necessary to adopt all of the various
advantageous features of the present disclosure into a single
composite tubular in order to realize their individual advantages.
Moreover, the scope of the invention is not to be limited to the
details disclosed herein, but is to be accorded the full scope of
the claims so as to embrace any and all equivalent apparatus and
methods.
* * * * *